- A part or segment, as of an organ.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
Examples from the Web for portio
This nerve is the portio major or superficialis of the nerve usually known as the ramus ophthalmicus superficialis in the adult.The Works of Francis Maitland Balfour, Volume III (of 4)
Francis Maitland Balfour
Deal with the ear, and remember that it has its portio mollis as you gently probe your way into its tube.